1. Field of the Invention
The present invention relates to an assembled battery, an exterior tube equipped battery to be used therein, and a manufacturing method of an assembled battery welded to a bus bar.
2. Description of Related Art
Japanese Patent Application Publication No. 2009-211908 (JP 2009-211908 A) describes an assembled battery including: a plurality of exterior tube equipped batteries each including a cylindrical battery and an exterior tube covering an outer peripheral surface of the battery; and a tray having a plurality of cylindrical partition wall members. In the assembled battery, the exterior tube equipped battery is inserted inside the cylindrical partition wall member so as to be accommodated in the tray. As the exterior tube equipped battery, such a battery is disclosed that: a cylindrical exterior tube made of thermally shrinkable resin is placed so as to cover an outer periphery of a cylindrical battery, and in this state, the exterior tube is heated so as to thermally shrink, so that the battery has a cylindrical exterior tube tightly adhered to an outer peripheral surface of the battery.
Further, in recent years, such an assembled battery has been proposed which includes: a holder having a front surface and a back surface and having a plurality of holding holes, which are cylindrical holes penetrating through between the front surface and the back surface; and cylindrical exterior tube equipped batteries inserted into the holding holes. In the assembled battery, in order to fix the exterior tube equipped battery into the holding hole of the holder, an outer peripheral surface (an outer peripheral surface of an exterior tube) of that part of the exterior tube equipped battery which is placed inside the holding hole is joined, by an adhesive, to that inner peripheral surface of the holder which constitutes the holding hole, for example.
In the meantime, in the above assembled battery, in order to electrically connect electrode terminals of adjacent batteries that constitute the assembled battery, for example, a bus bar is welded by resistance welding to an electrode terminal provided on a first surface placed on one end side of the cylindrical battery in an axis direction or on a second surface placed on the other end side thereof. More specifically, in a state where the bus bar is placed on the electrode terminal, a large load is applied to the bus bar in the axis direction of the battery by a welding electrode of a resistance welder, so as to weld the electrode terminal with pressure to the bus bar.